The present invention concerns flexible packaging, made from one layer film or from laminate, in particular the kind of packaging used for marketing food stuffs in bulky or granular form, and a sealing tape therefore.
Most flexible packaging is usually made up of a laminated plastic film constituted by two or more laminations, the plastics for the outside laminate being chosen with a view to preserve the contents of the bag, and to carry the printed text. The inside film is chosen so as to provide good sealibility. The film for the bag is chosen to be more or less flexible depending on the product to be packaged. The bag is sealed at least along one longitudinal seam and at two-cross seams. In order to open the sealed package, one of the seams generally is torn or cut.
If the products packaged in these bags are bulky, e.g. cheese, olives or the like, the bags will bulge considerably. If the products are granular, i.e. ground coffee or nuts and the like, they will be distributed in the bag which will then be more or less flat. In either case, the package must be reclosable, since all the contents are generally not removed at one time, i.e. when the bag is first opened. The reclosing of the bag and sealing it, in this condition to prevent damage to the contents, presents a great problem and many attempts have been made to find a suitable solution.
In one type of reclosable flexible packaging an adhesive tape is attached across the width of the entire bag, and when the latter has been partly emptied, the open end is folded over once or twice onto itself, the tape is removed and is reapplied partly across the end of the fold and partly across the bag.
The main drawback of this solution is the fact that the packaged bag is bulky and is thus distorted by its contents, and so the tape, which is less flexible than the film of the bag, loosens automatically via the ends thereof which lift away from the surface of the bag. This presents a problem in the handling of an unopened bag, since these ends will become attached to adjacent packaged bags. If the bag has been opened and resealed, the seal will become loose. In either case, the tape may become detached altogether. Another disadvantage of this solution is the fact that the tape will not seal properly when applied to a full bag and this will effect the shelf life of the product. Further, dust can adhere to the tape, preventing it from performing its function.
In another type of reclosable flexible packaging, an adhesive tape is provided across an opening in the bag. This opening may be an unsealed seam, a slit, or perforations which are to be torn to provide the opening. When the bag is to be opened, the tape is partially lifted and some of the contents are removed through this opening. Thereafter, the bag is held at the two ends of the opening and the ends are pulled away from each other to close the opening. The removed part of the tape is then pressed back to its former position.
The main drawback of this type of resealing is, as in the above mentioned type, the fact that the tape, when applied to a full bag, will not seal properly and therefore will adversely affect the shelf life of the product. Furthermore, if the contents of the bag are granular, they will adhere to the tape so that it can no longer perform its function.
A further consideration in making resealable flexible packaging is the attachment of the sealing means during or after the production of the bag itself which is accomplished with a minimum increase of costs.